R help - Nov 2006 - EM algorithm for truncated multivariate mixture of normals

I couldn't find a direct answer in CRAN to this question, so I'm asking
with some trepidation. I have a multivariate dataset (data.frame) with
columns that can be expressed as a set of mixed normals (at least I think)
and need to impute values that have constraints (truncated mixture of
normals where the values cannot be below zero). If there isn't a package
that can do this, is there a package similar to em.norm() that can be used
for truncated data?

I'm not sure if this is a pie in the sky question or not.

Thanks,
Jeff.